The present invention concerns a pressure-sensitive transducer arrangement having a matrix of transducer elements formed at the points of intersection of rows and columns of conductors. This transducer arrangement is intended particularly for use with industrial robots.
The PCT International Patent Publication No. WO 81/02223 discloses a pressure-sensitive transducer which has a matrix of transducer elements formed at the crosspoints of rows and columns of conductors (electrodes). This transducer arrangement comprises two piezoelectric polymer film layers made of polyvinylidene fluoride (PVDF), one provided with rows of conductors and the other with columns of conductors, and an electrically insulated intermediate layer sandwiched between them. This sandwich configuration is covered on each of the two flat, outer sides by an electrically conductive layer. In addition, perforated sheets may be placed over the two outer sides. The signal is generated by piezoelectric effect as a result of strain due to pressure on and bending of the piezoelectric layers.
In addition, capacitance-based pushbuttons (key) switches are known in which the compression of a dielectric medium causes a sudden change in capacitance. See, e.g., Elektronikschau, Vol. 9 (1980), p. 27. This change in capacitance is converted into pulses by means of appropriate circuitry. Since such keys have no mechanical contacts, they have a long useful life.
Finally, tactile sensors are known that contain conductive elastomers, conductive synthetic (plastic) materials, pressure-sensitive switching diodes, or piezo-resistive elements, as well as pneumatic switches. Such sensors, which have applications in industrial robots, are disclosed in the article "Sensors For Computer Controlled Mechanical Assembly" by S. Wang et al., The Industrial Robot (March, 1978), pp. 9-18. In the case of these sensors, however, it is difficult to reduce the individual sensor elements to the required dimensions in a cost-effective manner in order to realize a matrix with a smaller grid line spacing and, thus, a higher resolution as to location.